1. Field of Invention
The present invention relates generally to pneumatic tires and more specifically to light truck tires.
2. Description of Related Art
The effective operation of a pneumatic tire depends in part on retaining a quantity of air inside a tire at an elevated pressure. Many tire designers endeavor to retain the inflation pressure via the use of a tire component called a liner. The liner is typically made of a material which has a low air permeability, such as halobutyl. In U.S. Pat. No. 2,937,684 to Rockoff a liner made of butyl rubber is disclosed. Although liners manufactured of butyl and other air-impermeable materials have been somewhat successful in retaining a tire's inflation, some air loss has resulted from air diffusion through the bead area of the tire. Tire designers have sought to correct this problem by modifying the bead area to include air-impermeable rubbers, such as butyl. For example, U.S. Pat. No. 2,937,684 to Rockoff, U.S. Pat. No. 3,921,693 to Suzuki et al, and French Patent No. 1,528,941 disclose bead designs where the liner is extended toward the annular tensile members in order to improve air retention.